For the school's musical they sold student tickets and Adult tickets. A
student ticket is $4 and an Adult ticket is $8. Joel counted the tickets and
money. He said, twice as many student tickets as Adult tickets were sold.
The school collected $640 in ticket sales. Write an equation that models this situation t, tickets sold.

Step-by-step explanation:

Let's call students s and adults a.  If a student ticket cost $4, then the expression that represents that is 4s.  If an adult ticket cost $8. then the expresssion that represents that is 8a.

If the total amount of money collected for the tickets was $640, then

4s + 8a = 640.  But that's too many unknowns.  

Joes said that twice the number of student tickets were sold as adults; likewise you could say that half the number of adults tickets were sold as students.  Depends upon how you look at it.  Regardless, we need an expression in terms of either a or s.  I wrote adult tickets in terms of student tickets.  

If "twice the number of student tickets were sold as adult tickets", then

a = 2s

That says,"The number of adult tickets is 2 times the number of student tickets."  Subbing that into the equation above, we have

4s + 8(2s) = 640 and

4s + 16s = 640 and

20s = 640

That's the equation that represents that situation.

the answer

b. they are parallel and will never intersect.